PROJECT SUMMARY/ABSTRACT At least 2.8 million unpaid caregivers provide care to someone in the United States with a primary diagnosis of cancer. Cancer caregivers, in particular those of patients receiving an allogeneic bone marrow transplant (BMT), experience intense emotional, physical, and financial stress attributable to caregiving. Substantial evidence confirms the negative effects of stress among caregivers, for example, anxiety, depression, fatigue, disturbed sleep and poorer quality of life. However, few studies have examined the complexities of caregivers? stress responses in the allogeneic BMT context. Even fewer studies have addressed potential protective factors such as positive psychological states. To address this research gap, the proposed study will examine the experience of allogeneic BMT caregivers through the lenses of the Psychoneuroimmunology Framework and the Broaden and Build Theory of Positive Emotions. Aim 1 is to describe the allogeneic BMT caregiver?s experience over approximately 8-12 weeks following the patient?s BMT using a case-oriented approach and content analysis of qualitative (semi-structured interviews) and quantitative data (biomarkers, person reported outcomes). Aim 2 is to explore networks of relationships among psycho-neurological symptoms, positive psychological states, and caregiver health. This knowledge is essential for developing hypotheses that examine novel mechanisms which may protect caregivers from the effects of chronic stress on their health and quality of life. The proposed study is a rich longitudinal exploratory study of the complex and intense experiences of 10 to 12 allogeneic BMT caregivers. The proposed study and associated research training also provide a foundation for developing a new nurse scientist?s program of research focused on understanding the effects of chronic stress as a first step in developing interventions to maximize caregiver health and quality of life, and thus patient outcomes.